基于自然选择理论的动物利他行为研究

介绍了学术界关于动物利他行为的一些理论,包括群体选择理论、基因选择理论、亲缘选择理论、互惠利他理论、纯粹利他行为、操纵假说、相互依赖假说以及＂自私的基因＂理论。研究表明,自然选择学说能够很好地解释动物的利他行为,除此之外的其他学说只能用于利他行为的分类,而不能用来解释动物的利他行为。     

行为经济学视角下的“三农”政策有效性及改进方式

“三农”问题一直是政府工作的重中之重,而随着我国脱贫攻坚取得胜利,“三农”问题的核心也从“聚焦扶贫”转向“全面推进乡村振兴、加快农业农村现代化”。然而,“小农意识”导致农民群体存在非理性认知:现时偏见、禀赋效应、涉他偏好及沉没成本谬误。这些有限理性认知使得“三农”项目及政策的有效性在局部地区不及预期。本文尝试从行为经济学角度入手,通过经济学及心理学,思考农民群体非理性认知产生的原因,并结合行为经济学中的“助推”理论,对部分现有项目及政策进行改进,加强“三农”项目及政策的有效性。     

A mechanism for social selection and successful altruism

Within the framework of neo-Darwinism, with its focus on fitness, it has been hard to account for altruism behavior that reduces the fitness of the altruist but increases average fitness in society. Many population biologists argue that, except for altruism to close relatives, human behavior that appears to be altruistic amounts to reciprocal altruism, behavior undertaken with an expectation of reciprocation, hence incurring no net cost to fitness. Herein is proposed a simple and robust mechanism, based on human docility and bounded rationality that can account for the evolutionary success of genuinely altruistic behavior. Because docility-receptivity to social influence-contributes greatly to fitness in the human species, it will be positively selected. As a consequence, society can impose a "tax" on the gross benefits gained by individuals from docility by inducing docile individuals to engage in altruistic behaviors. Limits on rationality in the face of environmental complexity prevent the individual from avoiding this "tax." An upper bound is imposed on altruism by the condition that there must remain a net fitness advantage for docile behavior after the cost to the individual of altruism has been deducted.     

Temporary queens in metapolybia wasps: nonreproductive helpers without altruism?

In Metapolybia aztecoides some mated females produce only workers, losing in competition with other similar egg-layers before producing either males or queens. Worker production by these ultimately nonreproductive females may incidentally benefit others without lowering individual fitness (without "altruism"). It could be a by-product of mutualism rather than of kin selection or parental manipulation.     

The early radiation and relationships of the major arthropod groups

Cambrian arthropods are now well known, but there has been little agreement on how they contribute to an understanding of arthropod phylogeny. Fossils have either been lumped together as "trilobitomorphs" or, more recently, have been the subject of speculation invoking a multiple polyphyletic origin of arthropods. Cladistic analysis of characters of Cambrian and living representatives (excluding Uniramia) shows that trilobites and chelicerates are relatively advanced compared with "crustaceans," and there are doubts whether the latter constitute a national group. An undue emphasis on singular autapomorphies of problematic fossils has obscured these relationships in the past. "Trilobitomorphs" were simply an artificial taxon based on shared primitive characters. The arthropods that evolved during the Cambrian radiation show no more apparent morphological diversity than do the living groups. The evidence of wellpreserved problematica is critical to understanding the nature of this radiation and the affinities of the groups that remain today.     

Group competition, reproductive leveling, and the evolution of human altruism

Humans behave altruistically in natural settings and experiments. A possible explanation-that groups with more altruists survive when groups compete-has long been judged untenable on empirical grounds for most species. But there have been no empirical tests of this explanation for humans. My empirical estimates show that genetic differences between early human groups are likely to have been great enough so that lethal intergroup competition could account for the evolution of altruism. Crucial to this process were distinctive human practices such as sharing food beyond the immediate family, monogamy, and other forms of reproductive leveling. These culturally transmitted practices presuppose advanced cognitive and linguistic capacities, possibly accounting for the distinctive forms of altruism found in our species.     

A facultative gymnosperm from an interspecific cotton hybrid

A plant population from an interspecific cotton hybrid produces flowers with exposed ovules on petal margins. The variability of these abnormal flowers suggests the possibility that angiosperms may have evolved by accumulating regulator genes which narrow the range of response to fluctuations in the environment. Progressive canalization of development within a population like the "carpelloid petal" plants could have resulted in both angiospermy and speciation.     

Neural responses to taxation and voluntary giving reveal motives for charitable donations

Civil societies function because people pay taxes and make charitable contributions to provide public goods. One possible motive for charitable contributions, called "pure altruism," is satisfied by increases in the public good no matter the source or intent. Another possible motive, "warm glow," is only fulfilled by an individual's own voluntary donations. Consistent with pure altruism, we find that even mandatory, tax-like transfers to a charity elicit neural activity in areas linked to reward processing. Moreover, neural responses to the charity's financial gains predict voluntary giving. However, consistent with warm glow, neural activity further increases when people make transfers voluntarily. Both pure altruism and warm-glow motives appear to determine the hedonic consequences of financial transfers to the public good.     

Reducing the racial achievement gap: a social-psychological intervention

Two randomized field experiments tested a social-psychological intervention designed to improve minority student performance and increase our understanding of how psychological threat mediates performance in chronically evaluative real-world environments. We expected that the risk of confirming a negative stereotype aimed at one's group could undermine academic performance in minority students by elevating their level of psychological threat. We tested whether such psychological threat could be lessened by having students reaffirm their sense of personal adequacy or "self-integrity." The intervention, a brief in-class writing assignment, significantly improved the grades of African American students and reduced the racial achievement gap by 40%. These results suggest that the racial achievement gap, a major social concern in the United States, could be ameliorated by the use of timely and targeted social-psychological interventions.     

Physiological role of pleasure

A given stimulus can induce a pleasant or unpleasant sensation depending on the subject's internal state. The word alliesthesia is proposed to describe this phenomenon. It is, in itself, an adequate motivation for behavior such as food intake or thermoregulation. Therefore, negative regulatory feedback systems, based upon oropharingeal or cutaneous thermal signals are peripheral only in appearance, since the motivational component of the sensation is of internal origin. The internal signals seem to be complex and related to the set points of some regulated variables of the "milieu interieur," like set internal temperature in the case of thermal sensation (15). Alliesthesia can therefore explain the adaptation of these behaviors to their goals. Only three sensations have been studied- thermal, gustatory, and olfactory, but it is probable that alliesthesia also exists in such simple ways as in bringing a signal, usually ignored, to the subject's attention. For example, gastric contractions, not normally perceived, are felt in the state of hunger (16). Since alliesthesia relies on an internal input, it is possible that alliesthesia exists only with sensations related to some constants of the "milieu interieur" and therefore would not exist in visual or auditory sensations. As a matter of fact, luminous or auditory stimuli can be pleasing or displeasing in themselves, but there seems to be little variation of pleasure in these sensations, that is, no alliesthesia. There may be some esthetic value linked to these stimuli but it is a striking coincidence that they are in themselves rather neutral and that it is difficult to imagine a constant of the "milieu interieur" which could be possibly modified by a visual or an auditive stimulus-such as light of a certain wavelength or sound of a given frequency. In the light of this theory, it is possible to reconsider the nature of the whole conscious experience. The existence of alliesthesia implies the presence of internal signals modifying the concious sensations aroused from peripheral receptors. It is therefore necessary to question the existence of sensations aroused by direct stimulation of central receptors, such as hypothalamic temperature detectors, osmoreceptors, and others. Does their excitation arouse sensations of their own, or does the sensation have to pass through peripheral senses? Only human experimentation could answer this question. In the same way, it is possible that selfstimulation of the brain is pleasant, not by giving a sensation in itself, but because the electrical stimulus (17), renders peripheral stimuli pleasant.     

Should the History of Science Be Rated X?: The way scientists behave (according to historians) might not be a good model for students

I suggest that the teacher who wants to indoctrinate his students in the traditional role of the scientist as a neutral fact finder should not use historical materials of the kind now being prepared by historians of science: they will not serve his purposes. He may wish to follow the advice of philosopher J. C. C. Smart, who recently suggested that it is legitimate to use fictionalized history of science to illustrate one's pronouncements on scientific method (56). On the other hand, those teachers who want to counteract the dogmatism of the textbooks and convey some understanding of science as an activity that cannot be divorced from metaphysical or esthetic considerations may find some stimulation in the new history of science. As historian D. S. L. Cardwell has argued (57, p. 120): . . . [I]f the history of science is to be used as an educational discipline, to inculcate an enlightened and critical mind, then the Whig view . . . cannot do this. For it must emphasize the continuities, the smooth and successive developments from one great achievement to the next and so on; and in doing so it must automatically endow the present state of science with all the immense authority of history. He suggests that the critical mind might be inhibited by seeing the present as the inevitable, triumphant product of the past. The history of science could aid the teaching of science by showing that "such puzzling concepts as force, energy, etc., are man-made and were evolved in an understandable sequence in response to acutely felt and very real problems. They were not handed down by some celestial textbook writer to whom they were immediately self-evident" (57, p. 120). The past may give some hints on how to survive the most recent recurrence of public hostility to science. Rather than blaming historians such as Kuhn for encouraging antiscientific attitudes, as one physicist did in a public address in 1972 (58), one might consider this criticism of the older style of science history, published in 1940 by W. James Lyons (59, p. 381): The historians of science are responsible, it would appear, for the unpopularity of science among those most acutely affected by the depression. In their clamor to enhance the scientific tradition, and hoard for science all credit for the remarkable and unprecedented material advances which studded the century and a quarter preceding 1930, these historians have been more enthusiastic than accurate . . . science emerged [in the popular mind] as the most prominent force responsible for making this modern world so startlingly different from all preceding ages. Thus when, for many people, the modern world, in spite of all its resources, began to slip from its role of "best of all imaginable worlds," science came in for a proportionate share of blame. Had a more accurate picture of the part science has played been presented, science would not now be the object of so much suspicion and resentment. In more recent times, hostility to science has been intensified by the image of the "objective," robot-like scientist lacking emotions and moral values. If the new approach to the history of science really does give a more realistic picture of the behavior of scientists, perhaps it has a "redeeming social significance." Then, rather than limiting the conception of science to the strict pattern allowed by traditional local standards, one might try to change those standards in such a way as to reflect the freedom that the boldest natural philosophers have always exercised.     

Flying primates? Megabats have the advanced pathway from eye to midbrain

The pattern of connections between the retina and midbrain has been determined with electrophysiological and neuroanatomical methods in bats representing the two major subdivisions of the Chiroptera. Megachiropteran fruit bats (megabats), Pteropus spp., were found to have an advanced retinotectal pathway with a vertical hemidecussation of the kind previously found only in primates. In contrast, the microchiropteran bat Macroderma gigas has the "ancestral" or symplesiomorphous pattern of retinotectal connections so far found in all vertebrates except primates. In addition to linking primates and megachiropteran bats, these findings suggest that flight may have evolved twice among the mammals.     

高校图书馆开展"阅读优质服务月"活动的实践与思考

在"世界读书日"之际,我校图书馆为了"营造校园阅读氛围,延伸图书馆的服务功能",开展了以"书籍滋养心灵,阅读充实人生"为主题的阅读优质服务月活动,活动内容丰富,活动效果受到读者的广泛欢迎,总结活动规律,将会为今后开展此类活动留下宝贵的经验.     

Single-gene greenbeard effects in the social amoeba Dictyostelium discoideum

Selection can favor reproductive altruism if an altruism allele aids copies of itself by helping relatives. The alternative "greenbeard" mechanism, in which an allele directly recognizes and aids copies of itself in others, is generally thought to be too complex for a single gene to carry out. The csA gene in Dictyostelium discoideum acts as a single-gene greenbeard. When wild-type cells are mixed with csA-knockout cells, the wild type is more altruistic, but is also able preferentially to direct the benefits to other wild-type cells. Both properties derive directly from homophilic cell adhesion of the protein encoded by csA.     

An experimental study of the coloring problem on human subject networks

Theoretical work suggests that structural properties of naturally occurring networks are important in shaping behavior and dynamics. However, the relationships between structure and behavior are difficult to establish through empirical studies, because the networks in such studies are typically fixed. We studied networks of human subjects attempting to solve the graph or network coloring problem, which models settings in which it is desirable to distinguish one's behavior from that of one's network neighbors. Networks generated by preferential attachment made solving the coloring problem more difficult than did networks based on cyclical structures, and "small worlds" networks were easier still. We also showed that providing more information can have opposite effects on performance, depending on network structure.     

Mountain bluebirds: experimental evidence against altruism

The frequency of true altruism in nature requires assessment because, if true altruism is common, Darwin's theory of natural selection is inadequate to account for all of evolution. An experiment provided birds with the opportunity to behave truly altruistically. One member of each of 25 wild pairs was collected. Ten of these were replaced naturally by courting birds, or consorts. Only one consort fostered the young of her prospective mate, and her behavior was interpretable as a reproductive error. Other consorts behaved reproductively selfishly.     

Voyaging canoes and the settlement of polynesia

Sailing trials with two reconstructed Polynesian double canoes indicate that these craft can make good a course to windward up to approximately 75 degrees off the wind on long ocean voyages. This windward performance would have enabled Polynesians to exert a degree of control over their movements that would have been denied them had they only been able to sail or drift before wind and current. Indeed, without this windward sailing capacity there probably never would have been a Polynesian people today, for in a sense they are a product of their maritime technology. Had there been no great voyaging canoes, the settlement of Polynesia might have had to await the relatively late entry into the Pacific of the European navigators. But the Pacific was the scene of early innovation in weatherly sailing canoes, and as the European navigators "discovered" island after island, they were surprised to find that neolithic seafarers had preceded them into this vast ocean realm.     

Evolution of a nitrogen atmosphere on titan

Photochemical calculations indicate that if NH(3) outgassed from Titan it should have been converted to a dense N(2) atmosphere during the lifetime of the satellite. A crucial step in the process involves a gas phase reaction of N(2)H(4) with H. The most favorable conditions for this step would be the intermediate production of a CH(4)-H(2) greenhouse capable of raising the gas temperature to 150 degrees K. Subsequently about 20 bars of N(2) could have evolved. The pressure-induced opacity of 20 bars of N(2) should suffice to explain the recently measured 200 degrees K surface temperature. Unlike the situation on Jupiter, NH(3) is not recycled on Titan by reactions involving N(2) or N(2)H(4). This may explain the failure of recent attempts to detect NH(3) in the upper atmosphere of Titan.     

A terminal mesozoic "greenhouse": lessons from the past

The late Mesozoic rock and life records implicate short-term (up to 10(5) to 10(6) years) global warming resulting from carbon dioxide-induced "greenhouse" conditions in the late Maestrichtian extinctions that terminated the Mesozoic Era. Oxygen isotope data from marine microfossils suggest late Mesozoic climatic cooling into middle Maestrichtian, and warming thereafter into the Cenozoic. Animals adapting to climatic cooling could not adapt to sudden warming. Small calcareous marine organisms would have suffered solution effects of carbon dioxide-enriched waters; animals dependent upon them for food would also have been affected. The widespread terrestrial tropical floras would likely not have reflected effects of a slight climatic warming. In late Mesozoic, the deep oceanic waters may have been triggered into releasing vast amounts of carbon dioxide into the atmosphere in a chain reaction of climatic warming and carbon dioxide expulsion. These conditions may be duplicated by human combustion of the fossil fuels and by forest clearing.     

On being sane in insane places

It is clear that we cannot distinguish the sane from the insane in psychiatric hospitals. The hospital itself imposes a special environment in which the meanings of behavior can easily be misunderstood. The consequences to patients hospitalized in such an environment-the powerlessness, depersonalization, segregation, mortification, and self-labeling-seem undoubtedly countertherapeutic. I do not, even now, understand this problem well enough to perceive solutions. But two matters seem to have some promise. The first concerns the proliferation of community mental health facilities, of crisis intervention centers, of the human potential movement, and of behavior therapies that, for all of their own problems, tend to avoid psychiatric labels, to focus on specific problems and behaviors, and to retain the individual in a relatively non-pejorative environment. Clearly, to the extent that we refrain from sending the distressed to insane places, our impressions of them are less likely to be distorted. (The risk of distorted perceptions, it seems to me, is always present, since we are much more sensitive to an individual's behaviors and verbalizations than we are to the subtle contextual stimuli that often promote them. At issue here is a matter of magnitude. And, as I have shown, the magnitude of distortion is exceedingly high in the extreme context that is a psychiatric hospital.) The second matter that might prove promising speaks to the need to increase the sensitivity of mental health workers and researchers to the Catch 22 position of psychiatric patients. Simply reading materials in this area will be of help to some such workers and researchers. For others, directly experiencing the impact of psychiatric hospitalization will be of enormous use. Clearly, further research into the social psychology of such total institutions will both facilitate treatment and deepen understanding. I and the other pseudopatients in the psychiatric setting had distinctly negative reactions. We do not pretend to describe the subjective experiences of true patients. Theirs may be different from ours, particularly with the passage of time and the necessary process of adaptation to one's environment. But we can and do speak to the relatively more objective indices of treatment within the hospital. It could be a mistake, and a very unfortunate one, to consider that what happened to us derived from malice or stupidity on the part of the staff. Quite the contrary, our overwhelming impression of them was of people who really cared, who were committed and who were uncommonly intelligent. Where they failed, as they sometimes did painfully, it would be more accurate to attribute those failures to the environment in which they, too, found themselves than to personal callousness. Their perceptions and behavior were controlled by the situation, rather than being motivated by a malicious disposition. In a more benign environment, one that was less attached to global diagnosis, their behaviors and judgments might have been more benign and effective.